1. Field of The Invention
The present invention relates generally to a ribbon cartridge for a printer apparatus. Particularly, the invention relates to an ink ribbon cartridge for a heat sublimation or vapor type printer in which compatibility between the cartridge and an ink ribbon spool replacably mounted therein may be definitely established at the time of installation.
2. Description of The Related Art
Various types of ink ribbon cartridges are available for printing apparatus. Heat vaporization or heat sublimation printers generally use an ink ribbon having a sublimation dye thereon. The ribbon is arranged over a sheet of paper, or the like, on which an image is to be printed. Then a thermal head is energized in conformance with the image contours and heats the dye contained in the ink ribbon which is sublimated and transferred to the paper according to the thermal energy generated at the thermal head of the printer.
Some varieties of printers utilize an ink ribbon cartridge for full color printing in which a printing operation must be repeated several times, for example, three times for printing each primary color, magenta, cyan and yellow, resulting in a full-color image. In some such printers, a single ink ribbon cartridge is utilized in which an ink ribbon spool mounted therein is interchanged for printing each of the different colors.
One example of such a conventional. interchangable-spool type ink ribbon cartridge is disclosed in U.S. Pat. No. 5,290,114. The structure of such a cartridge is shown in FIGS. 6 and 7. As may be seen, the ink ribbon cartridge comprises an ink ribbon 1 having a predetermined length and wound around a main spool 2. A free end of the ink ribbon 1 is connected to a take-up spool 3 for being wound onto the take-up spool 3 according to printer operation. The cartridge body is formed such that the spools 2, 3 are rotatably supported and accommodated in a lower shell 4, and an upper shell 5 is mounted thereon. The main spool 2 and the take-up spool 3 have substantially identical bearing portions which will be described hereinbelow.
Each of the spools 2, 3 has a cylindrical shank 2a, 3a at a first end thereof which is slightly larger in diameter than the winding surface of the spools 2, 3. The other ends of each of the spools 2, 3 are provided with a smaller diameter rod-shaped shank 2b, 3b. Flange portions 2c, 2d, 3c, 3d divide the shank ends 2a, 2b, 3a, 3b from the main winding surface of the spools 2, 3 so as to define a winding area for the ink ribbon 1 between pairs of flanges 2c, 2d and 3c, 3d respectively.
The lower shell 4 includes a window 6 in a central portion thereof for allowing access of the thermal head (not shown). Annular bearing portions 7, 7 are integrally formed with a side wall 4a of the lower shell, openings defined in the annular bearing portions 7, 7 are sized to receive the cylindrical shanks 2a, 3a of the spools 2, 3. At the other side of the lower shell 4, second bearing portions 8, 8 are formed for receiving the rod-shaped shanks 2b, 3b of the spools 2, 3. The second bearing portions 8, 8 are formed as wall segments within the lower shell, each of the wall segments having U-shaped grooves 8a, 8a respectively formed therein for receiving the shanks 2b, 3b. A reinforcing rib 9 is provided between each of the second bearing portions 8, 8 and a side wall 4b of the lower shell 4, which is opposite the side wall 4a.
An upper shell 5 includes a side wall that engages with and is mounted to the side wall 4b and includes a cover portion 11 disposed over the rod-shaped shanks 2b, 3b and having internal structure to cooperate with the second bearing portions 8, 8 to rotatably mount the spools 2, 3 at each end thereof. The structure of the cover portion 11 cooperates with the bearing portions 8, 8 of the lower shell 4, and includes springs 10, 10.
For loading the spools 2, 3 into the lower shell 4, the cylindrical shanks 2a, 3a of the main and take-up spools 2, 3 are inserted into the annular bearing portions 7, 7 and the rod-shaped shanks 2b, 3b may simply be dropped into the U-shaped grooves of the second bearing portions 8, 8 for rotatably mounting the spools 2, 3 in the lower shell 4. The upper shell 5 may then be snapped on over the second bearing portions and the ribbon cartridge complete with the second, rod-shaped shanks being secured in a rotatably pressed state.
According to this, referring to FIG. 7, a width B of the U-shaped groove 8a of the second bearing portion 8 of the take-up spool 3 particularly, is made to be slightly larger than a width A of the rod-shaped shank 3b of the spool 3 for assuring easy rotation thereof in a mounted condition.
Accordingly, an appropriate-ink ribbon cartridge may be selected according to a color to be printed, ribbon/printer compatibility, type of printing to be performed, a winding orientation of the ink ribbon, or of a printing surface thereof, etc. However, according to the above described ink ribbon cartridge structure, in a detachable spool type cartridge wherein the same cartridge body is re-used while ink ribbon spools are changed according to the above-listed criteria, the above cartridge structure does not allow a user to verify compatibility of the spool with the cartridge or the printer or printing job to be accomplished. According to this, a user may easily install an inappropriate spool into the lower shell 4 of the cartridge. Such error may cause a printing operation to be flawed, or at worst, may cause jamming or malfunction of the printer due to incompatibility between the ink ribbon and the type of printer.
Thus, it has been required to provide a detachable spool type ink ribbon cartridge in which compatibility of the spool (and thus the ink ribbon) may be reliably established at the time of installation of the spool into the cartridge body.